1. Field of the Invention
The present invention generally relates to flat-panel display devices, and more particularly to a plasma display device.
A plasma display device is a flat-panel display device of a light-emitting type that displays picture information by selectively inducing discharges in a gas filled between a pair of glass substrates.
It is important for the plasma display device to increase resolution and reduce power consumption at the same time.
2. Description of the Related Art
FIG. 1 is a diagram showing a basic structure of a conventional common plasma display device 10. A structure similar to this is disclosed in Japanese Laid-Open Patent Application No. 2000-195431.
The plasma display device 10 is basically defined by a display panel 11 and first through third driving circuits 12A through 12C that cooperate with the display panel 11. The display panel 11 includes first discharge electrodes X1 through Xm and second discharge electrodes Y1 through Ym that are alternately arranged parallel to each other and extend in the X direction of FIG. 1. Further, the display panel 11 includes address electrodes Z1 through Zn that extend in the Y1 direction of FIG. 1 to intersect the first and second discharge electrodes X1 through Xm and Y1 through Ym. The first discharge electrodes X1 through Xm, the second discharge electrodes Y1 through Ym, and the address electrodes Z1 through Zn are selectively activated by the first through third driving circuits 12A through 12C, respectively.
For instance, an address voltage is applied between a selected one of the first discharge electrodes X1 through Xm (X2 in FIG. 1) and a selected one of the address electrodes Z1 through Zn (Z4 in FIG. 1), so that a discharge is started between the first discharge electrodes X2 and the address electrode Z4. Next, by applying a discharge-sustaining voltage between the first discharge electrodes X2 and the adjacent second discharge electrode Y2 by the driving circuits 12A and 12B, a discharge is started between the first discharge electrodes X2 and the second discharge electrode Y2 in a display cell selected by the address electrode Z4. The discharge is maintained while the selected display cell is activated.
It is required for such a plasma display device to increase resolution by narrowing pitches between electrodes and reduce power consumption at the same time.
FIG. 2 is a sectional view of the conventional plasma display panel 11, whose type is referred to as an ALIS (Alternate Lighting of Surfaces) type, taken along the Y direction of FIG. 1.
The display panel 11 of FIG. 2 is defined by glass substrates 11A and 11B opposed to each other, and a discharge gas is filled between the glass substrates 11A and 11B.
The glass substrate 11A may be referred to as a front or display-side substrate facing a viewer of the display panel 11, and the glass substrate 11B may be referred to as a rear substrate provided across the glass substrate 11A from the viewer.
More specifically, the glass substrate 11A has the first and second discharge electrodes X1 through Xm and Y1 through Ym alternately arranged with the same pitch on its side opposing the glass substrate 11B. The glass substrate 11B has the address electrodes Z1 through Zn formed on its side opposing the glass substrate 11A. The first and second discharge electrodes X1 through Xm and Y1 through Ym are formed of a transparent conductive film of ITO (In2O3·SnO2), and the first discharge electrodes X1 through Xm (ITO electrodes) has low-resistance bus electrodes x1 through xm formed thereon, respectively. Similarly, the second discharge electrodes Y1 through Ym (ITO electrodes) has low-resistance bus electrodes y1 through ym formed thereon, respectively. On the other hand, the address electrodes Z1 through Zn are formed of low-resistance metal patterns to extend in a direction to cross a direction in which the bus electrodes x1 through xm or y1 through ym extend. The first and second discharge electrodes X1 through Xm and Y1 through Ym and the bus electrodes x1 through xm or y1 through ym are covered with a dielectric film 11a on the glass substrate 11A, and the address electrodes Z1 through Zn are covered with a dielectric film 11b on the glass substrate 11B. Further, as is not shown in the drawing, fluorescent material patterns of red, green, and blue are applied and formed on the dielectric film 11b in accordance with display pixels.
In the display panel 11 of the above-described structure, discharges caused between the glass substrates 11A and 11B excite the fluorescent material patterns to produce light, which is emitted through the glass substrate 11A as indicated by arrow in FIG. 2.
FIGS. 3(A) and 3(B) are plan views of patterns of the first and second discharge electrodes X1 through Xm and Y1 through Ym formed on the glass substrate 11A in another conventional ALIS-type plasma display device including the display panel 11. The X and Y directions of FIGS. 3(A) and 3(B) correspond to those of FIG. 1.
In FIG. 3(A), the first and second discharge electrodes X1 through Xm and Y1 through Ym are formed of series of repeated T-shaped ITO patterns (electrodes) XT and YT extending from longitudinal sides of the corresponding bus electrodes x1 through xm and y1 through ym on the glass substrate 11A, respectively. Each ITO pattern has a tip part TA of a width A that extends in the extending direction of the bus electrodes x1 through xm or y1 through ym and a narrow neck part TB connecting the tip part TA and a corresponding one of the bus electrodes x1 through xm or y1 through ym. Each adjacent ITO patterns are arranged with a pitch corresponding to the resolution of the display panel 11, for instance, a pitch of 300 μm in FIG. 3(A), and a discharge is sustained in a gap (discharge gap) of a width g formed between each opposed ITO patterns XT and YT.
FIG. 4 is a diagram showing a structure of the glass substrate 11B of FIG. 2.
In FIG. 4, ribs 11C are formed with given pitches on the glass substrate 11B to extend in the Y direction of FIG. 1. Grooves G1 through Gn are formed between the ribs 11C, and the address electrodes Z1 through Zn are formed in the corresponding grooves G1 through Gn. Further, the address electrodes Z1 through Zn are covered with the dielectric film 11b in the corresponding grooves G1 through Gn, and the fluorescent material patterns R, G, and B of red, green, and blue, respectively, are formed on the dielectric film 11b. 
The glass substrate 11B of FIG. 4 is reversed to be placed on the glass substrate 11A so that, as shown in FIG. 5, the grooves G1 through Gn formed between the ribs 11C contain the corresponding ITO patterns XT and YT.
In the plasma display panel 11 of the above-described structure, a drive current for a discharge can be reduced by narrowing a width of the neck part TB of each ITO pattern XT or YT, and the discharge-sustaining voltage can be decreased by increasing the width A of the tip part TA of each ITO pattern XT or YT, or by decreasing the width g of the discharge gap.
If the plasma display panel 11 is to offer 1024×1024 resolution, letting its diagonal be 42 in., a pitch between each adjacent address electrodes Z1 through Zn must be set to 300 μm. However, in the case of such a high-resolution plasma display panel, where each rib 11C has a width of 60 μm and the tip part TA of each ITO pattern XT or YT has the width A of 160 μm, each rib 11C and each ITO pattern XT or YT adjacent thereto are only slightly separated by a margin δ. Therefore, if a deviation between the positions between the glass substrates 11A and 11B exceeds the margin δ, each rib 11C, as shown in FIG. 6, overlaps the tip part TA of each adjacent ITO pattern XT or YT, thus reducing the width A of the tip part TA.